1. Technical Field
The present invention relates to: a tape reel and a take-up reel, for winding recording tape thereon, such as magnetic tape, which is mainly used as a computer recording and reproduction medium; a recording tape cartridge with tape reel stored within a case; a drawing-out member for pulling out recording tape from a tape reel within a case; and a drive device for mounting a recording tape cartridge.
2. Related Art
Conventionally, recording tape cartridges are known for winding recording tape, such as magnetic tape, used as a data recording/reproducing medium for computers and the like, onto a single reel stored in a case. These recording tape cartridges are, for example, mounted in a drive device, and the recording tape is pulled out from an opening provided in the recording tape cartridge with a leader member. This pulled out recording tape passes between tape guides and a recording/reproduction head, and is taken up on a take-up reel disposed on the opposite side to that of the recording tape cartridge.
In particular, a method that has become prevalent is a method for recording/reproducing systems (drive devices) using recording tape cartridges with the recent increases in recording density, in which a recording/reproducing head is moved in the up-down direction by an actuator according to a servo signal that has been recorded on the recording tape in advance, the recording/reproducing head is caused to follow the servo signal, and a data signal is recorded/reproduced. The pulled out recording tape is thereby supported by plural tape guides within the drive device, and control, such that recording tape always runs past a predetermined position of the recording/reproducing head, is desired.
However, in reality, the running recording tape varies in the axial direction (up-down direction) of a hub (winding center) even though supported by the tape guides, and phenomena occur such as distorted winding of the wound recording tape, and one-layer sticking out, in which one rotation of recording tape sticks out from the winding surface. In FIG. 22, distorted winding states are illustrated of one-layer sticking out and of steps (it should be noted that, since the winding surface of the recording tape top tape edge is shown, one-layer sticking out or the like from the recording tape winding surface appears as peaks toward the recording tape bottom tape edge side).
For such distorted winding, the recording/reproducing head, moving in the up-down direction on the basis of the servo signal, which has been recorded in advance to the recording tape, is unable to follow the sudden displacements of the recording tape, particularly when fluctuations occur within small intervals of time (at high speed), and it becomes impossible to carry out the desired data signal recording/reproducing.
Furthermore, as servo tracking control improve, the allowable amount of fluctuation in the recording tape width direction, particularly for high frequency fluctuations (fluctuations within short time intervals), also decreases when running within the drive device. Namely, in a high recording density recording/reproducing system, the size of the recording signal is becoming finer, recording density is increasing, the size of the servo signal is decreasing, the recording density of the servo signal itself is increasing, servo tracking control methods are controlling at high frequencies, recording tape running speeds are increasing, and fluctuations in the recording tape of a level which previously would not have been a problem are now generating recording/reproducing errors of the data signal due to read errors of the servo signal.
A hub provided with a taper angle of 0.01 degrees to 0.1 degrees has been disclosed, with the hub using the larger external diameter side as the recording tape running base (in this case the upper side of the hub), and the recording tape running along the internal face of the upper flange (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2004-134060). That is, JP-A No. 2004-134060 discloses that when the hub is tapered, the recording tape is wound against the side of the hub with the larger external diameter.
However, often the recording tape adopts a curvature (width direction curvature), and such curvature of the recording tape has an effect on the winding position on the hub, with this effect often being greater than the effect due to tapering of the hub. Therefore, when rewinding the recording tape on the hub described in JP-A No. 2004-134060, there is a chance that the recording tape is wound along the inside face of the lower flange, depending on the direction of recording tape curvature.
Namely, even though the recording tape running base is the upper flange side, there is a chance that the recording tape runs along the lower flange side. Moreover, when the amount of recording tape curvature is large, sometimes the recording tape deviates too much toward one of the flanges and the tape edge is pressed hard against the flange, damaging the tape edge. This particularly becomes a significant problem as the recording tape gets thinner. Furthermore, sometimes if the recording tape is pressed too hard by one of the flanges, the reaction to such pressing leads to the occurrence of one-layer sticking out.
There is also a proposal for preventing recording tape winding distortion due to deformation of the hub as the tightening force (winding tension) of the recording tape against the hub increases, and the consequent gradual decrease in the upper and lower flange separation accompanying such distortion (see, for example, JP-A No. 2002-251859). However, the gradual decrease in the upper and lower flange separation due to hub distortion depends on the rigidity of the hub. JP-A No. 2002-251859 also does not refer to a hub formed with a taper.
There is also a proposal disclosed to neaten (to improve winding straightness) the winding shape (winding surface) by forming a reel in which the diameter of the outer peripheral face of the hub gets smaller at one end than at the other end, as winding of the recording tape progresses (see, for example, JP-A No. 2004-310827). In this proposal, the amount of taper of the hub increases as the winding amount of the recording tape on the hub increases. However, there is normally variation in the curvature direction and amount of curvature of recording tapes, and the running position of the recording tape relative to the hub moves, changing the winding shape (winding surface) on the hub. Due to this, such a reel may, however, actually worsen the recording tape winding straightness, and/or contribute to tape edge damage.